Posted
by
timothyon Monday September 28, 2009 @08:12AM
from the four-wings-perhaps-the-earliest-insult dept.

Wired reports on a find described September 24 in a note at Nature and the day after at the annual meeting of the Society of Vertebrate Paleontology: a dinosaur fossil bearing true feathers on four limbs. The fossil was discovered in northeastern China, in strata believed to have been deposited between 151 million and 161 million years ago. If that estimate is correct, the newly discovered Anchiornis huxleyi is at least one million years older than the believed age of the more famous winged dinosaur Archaeopteryx.

Where are all the transitional species? Everyone actually agrees that Archaeopteryx is a dead end so where are the primitive birds? The problem is the date for feathers keeps getting pushed back and there have even been early lizards found with what appear to be feathers. One massive gap is if birds evolved from dinosaurs where are all the tree dwelling dinos? The only ones seem to be Archaeopteryx and related protobirds. Odds are birds branched off very early on and were a separate line of evolution so saying birds evolved from dinosaurs is kind of like saying we evolved from chimpanzees. Closely related but separate lines. It's comforting to think dinosaurs survived by adapting but that's false since birds evolved long before the extinction and seem to go back to the early days of dinosaurs not the end of their reign. There's no question they were closely related it's just all the new evidence keeps pointing to an earlier and earlier separation and probably goes back to the time we were all essentially lizards.

Well, "fittest" means a lot more than "best". Fittest is about efficiency as well as ability. A human with 8 foot long legs could run really fast and use little energy, but would be less coordinated, more likely to trip because the nerve impulses would take too long to travel down to the leg to correct posture in time to catch itself from a fall. That's why most long legged animals have four legs (i.e. giraffe, moose, etc., which are all comically uncoordinated).

So a species that is "fittest" may not be the "best" species in an environment. It may simply be the most efficient design. Prevalence of resources is another important factor, an animal cannot be large and reproduce a lot of offspring, or it will destroy its own environment (humans?) and quickly go extinct. Long term success is about equilibrium with the environment, which is why small animals (drosophila, yeast, maybe even as big as cockroaches), are so successful. They exist sparsely and reproduce quickly with short generations, so that the species can easily maintain equilibrium with its environment.

The longer the generational gap and the greater the population, the more easily a species falls out of equilibrium with its environment.

Archaeopteryx really doesn't look all that different from the raptors that came before it, and still has a very dinosaur-like head and no beak. Is it a bird?

Back in the 1970s, when (Yale professor) John Ostrom was reviving the old debate over the relationship between birds and dinosaurs, he brought up a funny and informative piece of evidence: He pointed out that we actually had more Archaeopterix fossils than we thought. There were found in museums in Europe, classified as small dinosaurs.

He suggested that we not treat this as a misclassification at all, but rather as a tacit acknowledgement that those fossils were primitive birds and dinosaurs.

He also said that we need more such fossils, but I suppose everyone agreed with that. The basic problem here is that birds just don't fossilize very well.

I saw an example of this a few years ago. Due to my wife's allergies to furry critters, we have long had pet birds, mostly small parrots. Several of our cockatiels (and one friends') have been buried in a small raised strawberry/flower bed in the backyard. One spring, I decided to dig it up and sift out the rocks and roots of some large weeds (e.g., creeping bellflowers). I used a screen that was easily capable of separating out objects the size of their largest bones (skull, breastbone, etc). I found lots of small pebbles and roots, but no bones at all. In only a few years, their bones and beaks had been completely reduced to topsoil.

We lost two more of our small feathered friends last winter, both older than the 15 years they are expected to live, and they're buried in the center of the same bed. In a year or two, they'll be part of the soil, leaving behind no fossil evidence that they ever existed.

It takes some special, rare conditions for a bird to be turned into a fossil. Their adaptations for flight include very light, hollow bones. It's no mystery at all why the fossil record is so sparse.

... in beijing 10... archaeological site... fossilized remains proving that China was actually the birthplace of the human race.

Actually, with only a small amount of rephrasing, that's not much in conflict with one of the two competing theories of human development. One is the "Out of Africa" theory, that Africa has always been the center of human development, with people and their genes moving out of Africa, but rarely the other direction. The other is the "multi-center" theory, that people spread from Africa originally, but the slow flow of people and genes was essentially random, with a low level mixing in all directions.

There isn't any conclusive evidence. But everything that's known about humans at any stage is that most groups have always produced travellers, and travel along the coasts of the Atlantic, Mediterranean and Indian Ocean goes back as far as we can collect evidence of humans. Sailors have always been pretty good at gene mixing.

So most of the votes are with the "multi-center" theory. This would mean that there hasn't been a true center of humanity for at least tens of thousands of years, and maybe hundreds of thousands. Under this theory, each human gene variant has an origin, and our species is the sum of all these variants, each of which spread from wherever it first appeared. The oldest human settlements in the plains of eastern China would easily qualify as one "birthplace" of our species, along with the other centers in Africa and Europe.

The evidence about the Americas is much weaker. There seem to have been several major influxes of people through Alaska some 11,000 to 13,000 years ago. Knowing how humans build and use boats, it's unlikely that that was all the migration, and there were probably occasional travellers going both directions all the time, but we essentially have no specific evidence of it, only a few interesting "funny" remains. So the Americas may have been an outlier that provided little or no gene input to the rest of humanity before 500 years ago; we don't know.

But it is fairly well accepted that humans evolved first in Africa, spread out, formed a number of population centers, and have been mixing and exchanging genetic material ever since. So every major population center that existed, say, 50,000 years ago should be considered a "birthplace" of our species, in the sense that some useful genetic variation developed there and spread in the usual ways.

The only problem with the Chinese claim is that the word "the" in "the birthplace of the human race" implies uniqueness. China can't have been the only origin of humanity, though they are almost certainly an important "one of many" origins.

To get back on topic, China (especially Liáoníng) is also the origin of most of the avian fossils that we now have. There have been other important avian fossils in South America, and a few elsewhere.